Nova Southeastern University NSUWorks Biology Faculty Articles Department of Biological Sciences 8-22-2019 Avian Binocularity and Adaptation to Nocturnal Environments: Genomic Insights froma Highly Derived Visual Phenotype Rui Borges Universidade do Porto - Portugal Joao Fonseca Universidade do Porto - Portugal Cidalia Gomes Universidade do Porto - Portugal Warren E. Johnson Smithsonian Institution Stephen James O'Brien St. Petersburg State University - Russia; Nova Southeastern University, [email protected] See next page for additional authors Follow this and additional works at: https://nsuworks.nova.edu/cnso_bio_facarticles Part of the Biology Commons NSUWorks Citation Borges, Rui; Joao Fonseca; Cidalia Gomes; Warren E. Johnson; Stephen James O'Brien; Guojie Zhang; M. Thomas P. Gilbert; Erich D. Jarvis; and Agostinho Antunes. 2019. "Avian Binocularity and Adaptation to Nocturnal Environments: Genomic Insights froma Highly Derived Visual Phenotype." Genome Biology and Evolution 11, (8): 2244-2255. doi:10.1093/gbe/evz111. This Article is brought to you for free and open access by the Department of Biological Sciences at NSUWorks. It has been accepted for inclusion in Biology Faculty Articles by an authorized administrator of NSUWorks. For more information, please contact [email protected]. Authors Rui Borges, Joao Fonseca, Cidalia Gomes, Warren E. Johnson, Stephen James O'Brien, Guojie Zhang, M. Thomas P. Gilbert, Erich D. Jarvis, and Agostinho Antunes This article is available at NSUWorks: https://nsuworks.nova.edu/cnso_bio_facarticles/982 GBE Avian Binocularity and Adaptation to Nocturnal Environments: Genomic Insights from a Highly Derived Visual Downloaded from https://academic.oup.com/gbe/article-abstract/11/8/2244/5544263 by Nova Southeastern University/HPD Library user on 16 September 2019 Phenotype Rui Borges1,2,Joao~ Fonseca1,Cidalia Gomes1, Warren E. Johnson3,4,StephenJ.O’Brien5,6, Guojie Zhang7,8,9, M. Thomas P. Gilbert10, Erich D. Jarvis11,12, and Agostinho Antunes1,2,* 1CIIMAR/CIMAR, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Portugal 2Department of Biology, Faculty of Sciences, University of Porto, Portugal 3Smithsonian Conservation Biology Institute, National Zoological Park, Front Royal, Virginia 4Walter Reed Biosystematics Unit, Smithsonian Institution, Suitland, Maryland 5Theodosius Dobzhansky Center for Genome Bioinformatics, St. Petersburg State University, Russia 6Guy Harvey Oceanographic Center, Halmos College of Natural Sciences and Oceanography, Nova Southeastern University 7Section for Ecology and Evolution, Department of Biology, University of Copenhagen, Denmark 8China National GeneBank, BGI-Shenzen, Shenzhen, China 9State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China 10Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Denmark 11Laboratory of Neurogenetics of Language, Rockefeller University 12Howard Hughes Medical Institute, Chevy Chase, Maryland *Corresponding author: E-mail: [email protected]. Accepted: May 20, 2019 Abstract Typical avian eyes are phenotypically engineered for photopic vision (daylight). In contrast, the highly derived eyes of the barn owl (Tyto alba) are adapted for scotopic vision (dim light). The dramatic modifications distinguishing barn owl eyes from other birds include: 1) shifts in frontal orientation to improve binocularity, 2) rod-dominated retina, and 3) enlarged corneas and lenses. Some of these features parallel mammalian eye patterns, which are hypothesized to have initially evolved in nocturnal environments. Here, we used an integrative approach combining phylogenomics and functional phenotypes of 211 eye-development genes across 48 avian genomes representing most avian orders, including the stem lineage of the scotopic-adapted barn owl. Overall, we identified 25 eye- development genes that coevolved under intensified or relaxed selection in the retina, lens, cornea, and optic nerves of the barn owl. The agtpbp1 gene, which is associated with the survival of photoreceptor populations, was pseudogenized in the barn owl genome. Our results further revealed that barn owl retinal genes responsible for the maintenance, proliferation, and differentiation of photoreceptors experienced an evolutionary relaxation. Signatures of relaxed selection were also observed in the lens and cornea morphology-associated genes, suggesting that adaptive evolution in these structures was essentially structural. Four eye- development genes (ephb1, phactr4, prph2,andrs1) evolved in positive association with the orbit convergence in birds and under relaxed selection in the barn owl lineage, likely contributing to an increased reliance on binocular vision in the barn owl. Moreover, we found evidence of coevolutionary interactions among genes that are expressed in the retina, lens, and optic nerve, suggesting synergetic adaptive events. Our study disentangles the genomic changes governing the binocularity and low-light perception adaptations of barn owls to nocturnal environments while revealing the molecular mechanisms contributing to the shift from the typical avian photopic vision to the more-novel scotopic-adapted eye. Key words: relaxed and intensified evolution, pseudogenization, eye-development, coevolution, barn owl, ocular adaptations. ß The Author(s) 2019. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact [email protected] 2244 Genome Biol. Evol. 11(8):2244–2255. doi:10.1093/gbe/evz111 Avian Binocularity and Adaptation to Nocturnal Environments GBE Introduction vertebrate eye-development genes using comparative geno- mic approaches from 48 avian genomes representing most of Typically, birds have photopic vision (daylight). In contrast, the Downloaded from https://academic.oup.com/gbe/article-abstract/11/8/2244/5544263 by Nova Southeastern University/HPD Library user on 16 September 2019 the avian orders, including the stem lineage of barn owl (Jarvis barn owl Tyto alba (Strigiform order) is a nocturnal predator et al. 2014; Zhang, Li, Li, Li 2014 ). We assessed selective successfully adapted for scotopic vision (dim light). In addition, signatures and possible associations between orbit conver- the barn owl is well-adapted to a wide range of environments, gence and the developmental processes of ocular structures. ranging from temperate to tropical climates, and has one of Using this approach, we identified 25 eye-development can- the most extensive geographical distributions among birds didate genes with roles in the retina, lens, cornea, and optic (IUCN 2014). Barn’s owl remarkable adaptations are linked nerve that likely interact synergistically to increase the visual with its specialized predatory behavior and nocturnal lifestyle. sensitivity and binocular vision of the barn owl. They prey on rodents, small birds, lizards, amphibians, and invertebrates (IUCN 2014), relying on their acute hearing to define their prey’s position in total darkness (Coles and Guppy Materials and Methods 1988) and on their unique wing-feather design to identify Eye-Development Genes Sequences obstacles through a form of ecolocation (Bachmann 2007). Barn owls are typically nocturnal, but they also can be crepus- A Gene Ontology database was used to select a group of cular (active during twilight) (Lisney et al. 2012). genes involved in eye-development processes (GO: Concordantly, the anatomy of their eye differs greatly from 0001654) (The Gene Ontology Consortium 2015)basedon the standard pattern of other birds (fig. 1)(Hall 2008). The human and rat gene models and products. The respective barn owl has large and elongated eyes with outsized corneas protein sequences were used to perform TBlastN searches in and lens to achieve maximum visual sensitivity in nocturnal the barn owl genome (Avian Phylogenomics Project, Zhang, settings (Lisney et al. 2012; Orlowski et al. 2012), and that are Li, Li, Gilbert 2014), from which 211 genes were identified. frontally located to increase the binocular visual field The same procedure was implemented for an additional 47 (Orlowski et al. 2012). Furthermore, the barn owl has a avian genomes, overall encompassing 48 different species of scarcely evident fovea (region of the retina that is rich in most extant orders of birds (Jarvis et al. 2014)(supplementary cone photoreceptors and responsible for color discrimination table S1, Supplementary Material online). in bright environments), but instead has an abundance of rod cells (Harmening and Wagner 2011), which distinct from Phylogenetic and Branch-Specific Selection Analyses cones, gather light more efficiently in low-light (scotopic) envi- Nucleotide sequences were aligned using the MUSCLE algo- ronments (Hart 2001). Together, these features of the barn rithm (Edgar 2004) with the amino acid sequences and with owl eye mirror patterns observed in the mammalian eye, subsequent improvements by removing gap-rich sites. which has also been hypothesized to have evolved specialized Becauseweaimedtotracegeneevolutionwithinaframe- adaptations to nocturnal environments (Silva and Antunes